Particularly in cold environments, the collection and removal of sewage from houses, offices and other such buildings may present serious problems. In polar regions and other regions experiencing long periods of below freezing temperatures, conventional sewage removal systems incorporating pipes extending from buildings to a central treatment plant are often not practical, because of the problem of sewage freezing in the pipes. Where permafrost extends to a significant depth, the laying of sewage pipes becomes impractical or very expensive.
In recent times, sewage collection systems have been developed for buildings whereby sewage from toilets and other plumbing fixtures is fed to a holding tank for periodic removal by an external, sewage haul tank. Holding tanks may be inside the building, under the building or along side the building. One such tank is described and illustrated in U.S. Pat. No. 5,186,354 issued Feb. 16, 1993.
The relatively low flooring frequently found in housing in such polar areas, where the house rests on blocks or other such foundation on top of the permafrost, presents its own problems for sewage removal, since gravity flow of sewage to an inside or outside holding tank becomes impractical. As well, many of the conventional mechanical devices for handling sewage in more temperate climates, such as pumps, are prone to freezing and other forms of failure when subjected to the rigors of operating in extremely cold conditions with sewage fluids which may be of somewhat high viscosity. Such problems are compounded with low-water-use toilets because of the high solids ratio in the sewage.
As well, such conventional mechanical devices often require multiple valves for assisting in removal of the sewage from a toilet area to a holding tank area. Many such valves, of necessity, would be outside the insulated toilet area and hence, in an arctic environment, prone to seizing or other forms of mechanical failure. Thus, for instance, Soviet Union Patent No. 1,661,023 of Kalinin (July, 1991) which teaches a system of sewage removal for a toilet area to a holding tank on a train, requires multiple valves and would be entirely inappropriate and impractical for the harsh climatic conditions for which the present invention is intended.
Other known sewage removal systems require a standing vacuum condition in at least a portion of the system, for proper operation. Thus, for example, U.S. Pat. No. 4,713,824 of Oldfeldt, et al (December, 1987) teaches a vacuum toilet system where a standing vacuum in a part of the system is periodically accessed to draw waste from a toilet bowl. In a similar fashion, Ushitora, et al U.S. Pat. No. 5,100,266 (March, 1992) and Clear, et al U.S. Pat. No. 5,282,281 (February, 1994) teach sewage removal systems where parts of the systems are subjected to continuous or standing vacuum conditions in the line, with appropriate valve means and controls opening portions of the systems to the standing vacuum conditions for removal of sewage. Not only do such systems also require numerous and sophisticated valves, unsuitable for arctic conditions for reasons previously indicated, they also require relatively sophisticated vacuum generation and vacuum holding means. When it is considered that the system of the present invention is intended to be installed and operated in remote regions, where skilled trades people for installation and maintenance of the system may be unavailable for long periods at a time, it is again clear that such a system would be completely unsuitable for operation in the environment for which the present invention is intended.
It is an object of the present invention to provide a practical sewage removal system for low water use toilets in buildings in polar or cold climates. It is a further objective of the present invention to provide such a system which is inexpensive and practical to install, and reliable in operation.
It is a further object of the present invention to provide a system which will reduce the risk of freezing of sewage in pipes of the system, when the system is used in extreme, cold climates.
It is a further object of the present invention to provide such a sewage removal system which requires only low technology components, is virtually valve-free, and requires no standing vacuum conditions, for improved operation in environments of extreme cold and for ease of installation and maintenance in remote regions where skilled trades people may not be available.